This invention relates to abrasive metal blasting and spraying booth and supporting equipment. More specifically it relates to the equipment necessary for spraying a molten material for surface hardening and corrosion control.
The spraying or deposition of molten particles of metal, ceramic or other meltable material on a surface in order to improve its hardness, wear or resistance to corrosion is well known. The process employs either arc wire guns, combustion (oxygen acetelyne) wire guns, gas/powder guns or arc plasma to melt and spray the coating material at high temperatures onto receiving surfaces. The process creates a permanent bond between the sprayed material and the receiving base. It is used to build up worn parts, restoring them to their original dimensions, to provide protection from abrasion and wear, to control corrosion or to create a thermal or electrical barrier. The process requires that the surface to be sprayed be thoroughly cleaned and blasted to create a rough texture or "anchor tooth" designed to facilitate bonding.
The compressed air used to propel the molten material must be totally free of moisture, oil or other unwanted substances. This requires that the blasing and spraying be conducted under tightly controlled conditions in order not only to safeguard the quality of the work but also for the protection of the operators and the safeguard of the environment.
Because of these various requirements, thermal spraying has been restricted to in-plant operations. Yet, most applications, especially in the area of corrosion control, involve the treatment of heavy and bulky structures which cannot easily be transported to a processing plant. The technique could be applied to more reconstructive and maintenance works if the blasting and spraying could be conveniently conducted on location. This is particularly true in the field of marine equipment which can only be reconditioned on board ship or at some berthing sites which are usually distant from processing plants.